As is well known, commercially available lubricant compositions are prepared from a variety of natural or synthetic base stocks or blends of base stocks combined with various additive packages and solvents depending upon their intended application. For example, polyalkylene glycol (PAG) fluids have found use as the base oil in gearbox lubricants because of their better oxidation stability at high temperature when compared to mineral lubricating oils. Notwithstanding the oxidation stability of polyalkylene glycols, lubricating compositions based on these fluids are formulated with various additives such as antioxidants, corrosion inhibitors and the like to provide enhanced performance of the lubricating composition.
Formulating lubricating compositions to meet ever more stringent requirements is quite complex because of the potential interactions that may occur between the various additives that may be employed. Indeed, experience has shown that incorporation of one type of additive in a lubricant composition can have a negative impact on the function of another type of additive in that composition. For example, the presence of antiwear additives in a lubricant often reduces the oxidation stability of the formulation compared to one in which the antiwear additive is absent. Because oxidative degradation of oils increases with increasing temperature there is a need for lubricating composition that possess lowered oil temperatures under conditions of use.
Thus, one object of the present invention is to provide lubricating composition having lowered oil temperatures under conditions of use.
Another object of the invention is to provide a high efficiency polyalkylene glycol based oil composition for use in worm gears.
Yet another object of the invention is to provide food grade lubricants, i.e., lubricant compositions composed of components that are approved by U.S. DEPARTMENT OF AGRICULTURE or the National Sanitary Foundation (NSF).